1. Field of the Invention
The present invention relates to an orientation insensitive heat exchanger assembly for cooling an electronic device.
2. Description of the Prior Art
The operating speed of computers is constantly being improved to create faster computers. With this comes increased heat generation and a need to effectively dissipate that heat. As laptop computers become more universal, the ability to position these heat exchangers and other parts in any one of numerous orientations becomes of greater importance.
Heat exchangers and heat sink assemblies have been used that apply natural or forced convection cooling methods to dissipate heat from electronic devices that are highly concentrated heat sources such as microprocessors and computer chips; however, air has a relatively low heat capacity. Thus, liquid-cooled units called LCUs employing a cold plate in conjunction with high heat capacity fluids have been used to remove heat from these types of heat sources. Although, LCUs are satisfactory for moderate heat flux, increasing computing speeds have required more effective heat sink assemblies.
Accordingly, thermosiphon cooling units (TCUs) have been used for cooling electronic devices having a high heat flux. A typical TCU absorbs heat generated by the electronic device by vaporizing a working fluid housed on the boiler plate of the unit. The boiling of refrigerant constitutes a phase change from liquid-to-vapor state as such the refrigerant of the TCU is considered to be a two phase fluid. Vapor generated during boiling of the refrigerant is then transferred to a condenser, where it is liquefied by the process of film condensation over the condensing surface of the TCU. The heat is rejected into a stream of air flowing over fins extending from the condenser and the condensed liquid is returned back to the boiler plate by gravity. As a result, most TCUs must be positioned in a predetermined orientation in order for the refrigerant to continue the boiling-condensing cycle, thus making the TCU orientation sensitive.
To solve this problem orientation insensitive thermosiphons, or heat exchangers, have been used. An example of a heat exchanger is U.S. Pat. No. 5,076,350 to Grantz et al. Also relevant is U.S. Pat. No. 4,550,774 Andres et al.
The '350 patent is a heat exchanger assembly including a housing for holding coolant. The housing defines a plurality of condensing chambers and a plurality of channels. These channels are hermetically sealed from the coolant disposed in the housing and do not permit coolant to flow into them, but around them.
The '774 patent is a heat exchanger assembly and discloses a housing defining a plurality of condensing chambers and channels for dissipating heat from an electronic device. The channels are mutually crossing or intersecting in at least two directions and distribute heat from an electronic device, regardless of the orientation of the heat sink.